1. Field of the Invention
The present invention relates to a wheel for in-line skates, and more particularly to a wheel for in-line skates which enables a user to improve an acceleration from standstill on a surface, in which the ability is estimated by a time period required to accelerate from a standstill to a certain speed or to travel from the standstill to a certain distance.
2. Description of the Prior Art
Referring to FIGS. 1 and 2, there is shown a conventional in-line skate 1. As shown in FIGS. 1 and 2, the in-line skate 1 is generally comprised of a shoe or boot 2 adapted to receive a user's foot, a frame 3 fixedly attached to a bottom surface of the boot 2, and a series of wheels 4 rotatably supported to the frame 3. Each of the wheels 4 comprises a central hub 5, an annular tire 6 provided on an outer surface of the central hub 5, and a bearing assembly 7 fitted in the central hub 5.
In games played while wearing such an in-line skate 1, such as racing, aggressive inline skating, hockey and the like, it is advantageous for a user to achieve a high speed in a short time period. That is, the acceleration from standstill is a very important factor in determining a user's (skater's) competitive power.
Since the in-line skate 1 and the wheels 4 are not provided with means for improving a user's acceleration from a standstill, the acceleration which can be achieved on a surface, will depend on only a user's muscle power. The user's power has a certain limit and is gradually decreased with time, because the user's power is not obtained by a mechanical device. Accordingly, although a user makes efforts to enhance his muscle power and to improve his skating skill over a long term, improvement of his accelerating ability from a standstill is negligible. As a result, it is expected that a user's acceleration from a standstill can be improved by wheels with an improved structure.
Recently, with the increase in popularity of in-line skates, a large number of patents relating to in-line skates, particularly to wheels of the in-line skate, have been proposed. Most of the patents relate to bearing assemblies 7 of the in-line skate, and some patents relate to the tire 6 of the in-line skate. For example, U.S. Pat. Nos. 5,441,286, 5,964,469, 6,065,760 and 6,142,578, and Japanese Patent Laid-open No. 11-235411 propose structures of the bearing assemblies considering economical efficiency. U.S. Pat. Nos. 5,813,678, 5,893,569, 6,019,378 and the like propose structures of tires for achieving quick stop, referred to as a “hockey-stop”. However, the wheels proposed in the above-mentioned patents are not provided with means for improving a user's acceleration from a standstill, like the wheel 4 illustrated in FIG. 2.